1. Technical Field
The present disclosure relates to surgical fastener applying apparatus. More particularly, the present disclosure relates to a fastener applying assembly that includes a plurality of two-part surgical fasteners configured to apply varying compressive forces to tissue.
2. Background of the Related Art
Many varieties of surgical fastening apparatus are known in the art, some of which are specifically adapted for use in various surgical procedures including, but not limited to, end-to-end anastomosis, circular end-to-end anastomosis, open gastrointestinal anastomosis, endoscopic gastrointestinal anastomosis, and transverse anastomosis. U.S. Pat. Nos. 5,915,616, 6,202,914, 5,865,361, and 5,964,394 each describe one or more suitable apparatus which may be employed while performing one of these procedures.
In general, a surgical fastening apparatus will include an anvil that is approximated relative to a fastener cartridge during use or a fastener cartridge that is approximated relative to an anvil. The anvil includes depressions that are aligned with, and/or are in registration with slots defined in the cartridge, through which the fasteners will emerge, to effectuate formation. In other apparatus, the anvil contains a plurality of retainers with apertures to receive legs of the fasteners. The fastener cartridge typically has one or more rows of fasteners disposed laterally or radially of a channel that is configured to accommodate a knife, or other such cutting element, such that tissue can be simultaneously cut and joined together. Depending upon the particular surgical fastening apparatus, the rows of fasteners may be arranged in a linear or non-linear, e.g. circular, semi-circular, or otherwise arcuate configuration.
Various types of surgical fasteners are well known in the art, including but not limited to unitary fasteners and two-part fasteners. Unitary fasteners generally include a pair of legs adapted to penetrate tissue and connected by a backspan from which they extend. In use, subsequent to formation, some of the unitary fasteners have a “B” configuration. Typically, the two-part fasteners include legs that are barbed and connected by a backspan which are engaged and locked into a separate retainer piece that is usually located in the anvil. In use, the two-part fastener is pressed into the tissue so that the barbs penetrate the tissue and emerge from the other side where they are then locked into the retainer piece. The retainers prevent the two-part fastener from dislodging from the tissue. The two-part fasteners are not intended to be unlocked or removable and are generally made of a bioabsorbable material.
During each of the aforementioned surgical procedures, the tissue is initially gripped or clamped between the cartridge and anvil such that individual fasteners can be ejected from the cartridge, through the slots, and forced through the gripped tissue. Thereafter, the fasteners are formed by driving them into the depressions formed on the anvil or into the apertures of the retainers.
A common concern in each of these procedures is hemostasis, or the rate at which bleeding of the target tissue is stopped. It is commonly known that by increasing the amount of pressure applied to a wound, the flow of blood can be limited, thereby decreasing the time necessary to achieve hemostasis. To this end, conventional surgical fastening apparatus generally apply two or more rows of fasteners about the cut-line to compress the surrounding tissue in an effort to stop any bleeding and to join the cut tissue together. Each of the fasteners will generally apply a compressive force to the tissue sufficient to effectuate hemostasis, however if too much pressure is applied, this can result in a needless reduction in blood flow to the tissue surrounding the cut-line. Accordingly, the joining of tissue together in this manner may result in an elevated level of necrosis, a slower rate of healing, and/or a greater convalescence.
Consequently, it would be advantageous to provide a surgical fastening apparatus capable of limiting the flow of blood in the tissue immediately adjacent the cut tissue to effectuate hemostasis and wound closure, while maximizing blood flow in the surrounding tissue to facilitate healing.
Additionally, when tissue is clamped and compressed between the anvil and cartridge, some of the fluid of the tissue is squeezed out so the tissue is compressed further at the center portions of the cartridge and anvil than at the lateral edges, thereby leaving thicker tissue at the edges. It would therefore be advantageous to provide staples which could better accommodate these resulting different tissue thicknesses.